WASHINGTON (CNN) -- The Air Force has grounded its fleet of B-2 stealth bombers because of a problem with the ejection system used by the crew.

"The suspension is the result of a potential problem associated with initiators which operate the air crew ejection system. The manufacturer discovered the potential flaw in the initiators during routine acceptance testing," the Air Force said in a statement.

Eight initiators on the eight B-2s now in service, which are stationed at Whiteman Air Force Base in Missouri, will be replaced. The Air Force did not say how long that might take.

Lt. Col. Ed Whorley, an Air Force spokesman, said the bat- winged planes could be reactivated on short notice if they are needed for combat operations.

The B-2 bombers cost $2 billion each. The Air Force is in the process of buying 20 of the costly aircraft.

The plane can drop either nuclear or conventional bombs and is designed to be able to dodge radar in combat situations. It is covered with special materials that enable it to absorb or deflect radar signals and thus avoid detection.

Reuters contributed to this report.